Like it mixed with ice and slice of lemon (9)
I believe the answer is:
identical
'like' is the definition.
(I've seen this before)
'it mixed with ice and slice of lemon' is the wordplay.
'mixed with' is an anagram indicator.
'slice of lemon' becomes 'l' (I can't explain this - if you can you should give a lot more credence to this answer).
'ice'+'and'='iceand'
'it' anagrammed with 'iceand' gives 'identica'.
'identica'+'l'='IDENTICAL'
Can you help me to learn more?
(Other definitions for identical that I've seen before include "showing no change" , "Indistinguishable" , "lacking distinction" , "Selfsame" , "as B and B" .)